How to block the Internet & things on the Internet?
From my last post, you might have learned the reasons of why things are blocked and what are blocked on the Internet. Now, let us move ahead to understand the techniques on how to block the internet, since this is what would help you know and understand how to unblock websites and others on the Internet in a much easier way.
There is a variety of techniques, methods, and tools that organizations, companies, and colleges use to block content on the Internet. But before going any further with how to unblock sites, there are some basic technical Internet-related terms that we must discuss. This is so that the rest of the articles are easy and straightforward to understand.
Every computer connected to the Internet has a unique IP address given to it. An IP address is basically the computer’s identity on the Internet through which it can be contacted. Every computer has its own IP address, and that is what you use to unblock sites. It looks like 22.214.171.124. You can also find your computer’s IP address by simple starting your browser and connect to the website http://www.whatismyipaddress.com.
You can find out a website’s IP address by simply going to MS-DOS or command prompt and type the command, like for www.google.com – ping google.com. Within a few seconds in the output, the IP address of google.com will be displayed(in this case it would be 126.96.36.199.
It is complicated to remember an IP address for a website. Imagine, if you had to remember it to open each site, it would be a nightmare. Every website has an IP address along with a domain name. A domain name is an easy name to remember for a site; an example is www.facebook.com. Home computers do not have a domain name like the websites.
Domain name system(DNS) Lookups
The process of changing the domain name into the specific IP address is called a DNS lookup. Your browser performs a DNS lookup automatically in the background each time you type a website address or domain name in your browser. Without a DNS lookup, a browser will not know the IP address of the website you wish to connect to and hence will not know how to connect to it. This is also something you need to know to understand how to unblock blocked sites.
Reverse DNS lookup
It is the exact reverse process of converting an IP address into its respective domain name.
A DNS server is a server that handles DNS lookup queries from the browser/users and sends back replies to them. Every organization has its own DNS server that will manage the local user’s DNS lookup requests.
This stands for HyperText Transfer Protocol. It is the communication protocol that is normally used by your browser to communicate with websites. It contains all the rules that browsers follow to communicate with a remote website. The secure form of HTTP which allows users to have encrypted communication with a website is known as HTTPS. Understanding this would help you understand the idea of how to unblock sites.
A port is a door through which data enters or leaves your computer. Typically ports are used to exchange data between different devices. There are two types:
- Hardware ports: All of us use hardware ports like the USB port, Ethernet port, etc. These are normally used to exchange data between two devices.
- Virtual ports: All web applications on your computer open something known as virtual ports on your computer to communicate with remote servers on the Internet. Without virtual ports, there would be no way for applications on your computer to communicate with remote servers on the Internet. You can find a list of open virtual ports on your computer by merely going to the MS-DOS prompt and typing the command netstat -n.
A proxy server is a server or software that acts as an intermediary between a user and the Internet. Whenever a user sends a request to get a webpage to a proxy server, it will forward that appeal to the relevant server on the Internet and then send back the response to the person. This is a technology used to unblock the blocked sites.
Based on the above, it is evident that a proxy server can be used to protect one’s identity on the Internet. Typically your computer will directly send a request to a website, and the site will know your computer’s identity or IP address. However, if you utilize a proxy server to send the request to a website, then the website will think that the proxy server is connecting to it. But actually, it is you who is using a proxy server to link to a remote site anonymously, which helps you unblock websites that have been blocked.
Moreover, since a proxy server acts as an intermediary between a user and the Internet, it can be used to block access to some websites and prevent the user from connecting to them. A lot of governments, companies, and colleges utilize the proxy server to block the websites. They add a list of banned sites to restrict access to these sites.
On the other hand, some proxy servers do not restrict or block access to any websites on the Internet. So many users, instead of connecting to the proxy servers of their office or college, will simply connect to a proxy server that does not block anything to gain uncensored access to the entire Internet. This is another method how to unblock sites.
Popular Types of Proxies
Although there are different types of proxy servers available on the Internet, the most popular are the following:
- Web proxy or HTTP proxy: It is a type of a proxy server that primarily is used to connect users with websites on the Internet using the HTTP protocol. Usually, a web proxy server will accept the requested web address in an input box within the browser window.
- DNS proxy: It is a type of proxy server that takes the DNS queries from the browser on a local network. After that, it forwards them to the nearest DNS server.
- SOCKS proxy: It is a type of proxy server that allows linking to a remote server using all different protocols. These protocols include TCP, UDP, FTP, etc. Its use is not just restricted to giving users access to websites.
Techniques on How to block the Internet & things on the Internet?
Different techniques are used by governments, companies, and colleges to censor the Internet and block access to websites and content on the Internet. So, you need to understand them so that you know how to unblock blocked sites on your own. The methods are:
Domain name filtering
Whenever you type a domain name in any browser, a DNS lookup query is sent to the local DNS server. It may be possible for a college or company to block DNS lookups for some domain names. If a browser cannot perform a DNS lookup for a particular domain, then it cannot access it. For example, if a network blocks DNS lookups for the Gmail server and the Google Talk server, then you will not be able to use your Google Talk Instant Messenger application. And this is since it will not be able to connect to Google Talk server.
IP address filtering
In such a filtering technique, instead of blocking domain names at the DNS server level, access to certain IP addresses are blocked by the network administrator.
A lot of organizations will make all users connect to the Internet via a proxy server. The proxy server will monitor all the websites that users are trying to access. And they can be configured to block or redirect a user. This is in case they try to access a website that the organization chooses to block. There are ways to bypass this and unblock the sites.
In such a filtering technique, the entire URL address is scanned for certain blocked domains or keywords. In case any blocked domain or keyword is found, then the user is blocked and denied access to the respective website.
In order to function properly, some web applications open certain predefined local ports on your machine or establish outgoing connections to certain predefined ports on the remote machine. Without this, the applications cannot function and communicate on the Internet. To block the use of some application, many network administrators will simply block the respective ports it uses to function. Such a technique effectively blocks the use of those respective applications. For example to block Torrents or Skype, port blocking is used.
Advance packet filtering
In such a filtering technique, the transmission between a user and a remote website is monitored for certain keywords. And as soon as any blocked keywords are detected, then the connection is reset or disconnected. You can bypass this and unblock the sites easily. The methods would be shared in the next articles.
Some organizations like to limit the amount of data a particular user can download in a predefined time period. As soon as that limit is reached, then the user’s access to the Internet is taken away. Instead of a data limit, some organizations also put a time limit on the Internet access of a user.
This is normally seen only in case of emergency or unusual situations when a government disconnects users from the Internet completely. And this is done by removing the link between the user and the Internet.
Many governments and organizations will allow users to search for only certain keywords on Google or access only specific videos on YouTube. This filtered access is also commonly used by blocking mechanism.
Now that we know how to block the Internet and the things on the Internet, you would have also understood how the organizations block content on the Internet. In the next post, you would see how to unblock the sites after they have been blocked.
If you feel any method or point has been missed out, do share it in the comments. Also, for any doubts, feel free to comment below about it.